1. Field of the Invention
The present invention relates to a transport system, and in particular to a transport system that supplies and removes articles without causing a processing device to wait.
2. Description of the Related Art
There is need for articles such as FOUPs (sealed cassettes for transporting semiconductor wafers) to be supplied to and removed from the loading ports of devices such as a semiconductor machining device and a semiconductor inspection device without causing such devices to wait. For this reason, it has been proposed to provide a buffer in the vicinity of a processing device, and provide a second transport device for performing transport between the buffer and the processing device. For example, in JP 2006-224944A, multiple overhead travelling vehicle tracks are disposed in parallel in a ceiling space, one of which is used for long-distance transport, and another of which is used for short-distance transport. A buffer is disposed under the track for long-distance transport, and the loading port of a processing device is disposed under the track for short-distance transport. The overhead travelling vehicle for long-distance transport performs the delivery and receipt of articles with the buffer, and the overhead travelling vehicle for short-distance transport performs the delivery and receipt of articles between the buffer and the loading port. Accordingly, if articles required by the processing device have been transported to the buffer in advance, the articles can be quickly supplied to the processing device. Also, the overhead travelling vehicle for short-distance transport quickly removes articles from the loading port of the processing device. However, this configuration requires providing tracks at the same height position in parallel, thus increasing the floor space occupied by the transport system in a plan view.
In JP 2005-150129A, a buffer including a transport device is provided in front of a processing device, an overhead travelling vehicle performs the delivery and receipt of articles with the buffer, and the transport device of the buffer performs the delivery and receipt of articles with the loading port. However, a display for indicating the operation state, an operation panel for manual operation, and the like are provided on the front surface of the processing device, and it is not preferable for them to be blocked by the buffer. Also, the loading port is used not only by an automatic transport device, but also for manual supply and removal of articles, and manual access is difficult if the front surface of the processing device is covered by the buffer.